262 



BIOLOGY OF THE SEAS OF THE U.S.S.R. 



are very severe. For seven months (November to May) the temperature of 

 even the surface waters remains below —1-5° (—1-6° to —1-8°); in June, 

 September and October it keeps at about 0°, and only in July and August, 

 off the coast, does it rise to 3°, 5° or 7° (monthly average). Only in the south- 

 western part of the Sea, in the region of the Bering Strait, does the temperature 

 at times rise to 12° to 14° in the summer. The deeper layers of water (except 



WK 



Fig. 111. The Chukotsk Sea showing depths, direction of the warm (2) and cold 

 (3) currents and the summer boundary of the ice (/) (Ushakov). 



for the eastern part of the Sea) have a temperature of almost 0° even in the 

 summer (Fig. 1 12). In the northern parts of the Sea, near the open, deep parts 

 of the Arctic basin, a curious temperature range is observed in the summer : 

 ' the influence of the warm waters of the Bering Strait is still felt in the surface 

 layer down to 20 m. The temperature reaches 2° to 3° ; lower down, at a depth 

 of 100 m, there are Arctic waters with a temperature of up to —1-7°; still 

 lower a heating effect is observed and at a depth of 150 m the temperature is 

 0° ' (Ratmanov, 1939). This is as far as the influence of the intermediate warm 

 layer extends to the east. 

 The salinity range of the Chukotsk Sea shows a good many variations. 



